Biomass, in particular biomass of plant origin, is recognized as an abundant potential source of fuels and specialty chemicals. See, for example, “Energy production from biomass,” by P. McKendry—Bioresource Technology 83 (2002) P 37-46 and “Coordinated development of leading biomass pretreatment technologies” by Wyman et al., Bioresource Technology 96 (2005) 1959-1966. Refined biomass feedstock, such as vegetable oils, starches, and sugars, can be substantially converted to liquid fuels including biodiesel (e.g., methyl or ethyl esters of fatty acids) and ethanol. However, using refined biomass feedstock for fuels and specialty chemicals can divert food sources from animal and human consumption, raising financial and ethical issues.
Alternatively, inedible biomass can be used to produce liquid fuels and specialty chemicals. Examples of inedible biomass include agricultural waste (such as bagasse, straw, corn stover, corn husks, and the like) and specifically grown energy crops (like switch grass and saw grass). Other examples include trees, forestry waste, such as wood chips and saw dust from logging operations, or waste from paper and/or paper mills. In addition, aquacultural sources of biomass, such as algae, are also potential feedstocks for producing fuels and chemicals. Inedible biomass generally includes three main components: lignin, amorphous hemi-cellulose, and crystalline cellulose. Certain components (e.g., lignin) can reduce the chemical and physical accessibility of the biomass, which can reduce the susceptibility to chemical and/or enzymatic conversion.
Producing fuels and specialty chemicals from biomass can require specialized conversion processes and/or refineries, which are distinct from and incompatible with conventional petroleum-based conversion processes and refineries. Thus, the wide-spread use and implementation of biomass to produce fuels and specialty faces many challenges, because large-scale production facilities are not widely available and are expensive to build. Furthermore existing processes can require extreme conditions (e.g., high temperature and/or pressure, which increases capital and operating costs), require expensive catalysts, suffer low conversion efficiency (e.g., incomplete conversion or inability to converts ligno- and hemi-cellulosic material), and/or suffer poor product selectivity.
Another challenge to the use of biomass feedstock to produce fuel or specialty chemical products is high acidity (i.e., low pH) in bio-oil intermediates produced from pyrolyzing the biomass feedstock. High acidity can cause problems such as corrosion in conventional fluid catalytic cracking (FCC) equipment and thus can require costly upgrades to conventional FCC units to resist corrosion (e.g., upgrades with exotic, corrosion-resistant alloys such as a HASTELLOY® alloy available from Haynes International, Inc.).